REGIOSELECTIVITY OF THE STEP OF OLEFIN INSERTION INTO A PD-C BOND IN THE HECK-REACTION

To study the factors affecting the regioselectivity of the Heck's aryl ation, several olefins were tested in which the substituents had diffe rent electron and steric characteristics. It was found that the type o f aryl addition to a sterically unhindered olefin barely depends on th e location of effective charges at the carbon atoms of the vinyl group , although it does depend on the LUMO coefficients of the atomic orbit als on the carbon atoms of an olefin. This fact points to the orbital control of the reaction. It was shown that regiospecific formation of alpha-products from 2-monosubstituted and 2,3-disubstituted 1-vinylpyr roles is stipulated by steric factors.